It is common for people, especially family members, to share wireless communication devices, such as mobile phones. For example, a parent may purchase a mobile phone and lend it to a child during the day so that the child can call the parent when the child needs to be picked up from school. After being picked up, the child may return the mobile phone to their parent, who may use the mobile phone during the evening.
Over time, capabilities have been added to mobile phones allowing mobile subscribers to have access to more and more services. Mobile phones are not just for phone calls anymore. A mobile subscriber can now check their e-mail, send photos, and make on-line purchases using their mobile phone. The amount of content that can be accessed by the subscriber seems almost limitless. However, not all content is appropriate for children.
Providing adult content is a big business. However, this type of content should not be accessed by children. In fact, it may be illegal to allow children to access adult content. When both adults and children are using the same mobile phone, there needs to be some mechanism that prevents children from accessing the adult content, while still allowing adult access.
The already existing security mechanisms (terminal+SIM card+PIN) used by mobile operators are not sufficient. The maintenance and personal delivery of additional PINs is also a problem (at least from a commercial point of view). Other already existing PINs (e.g., i-mode PIN) can be switched off to simplify usage for other content types. Thus, additional barriers need to be implemented.